how to update the content of a TextView from a non-GUI thread

["Hao Song" <baritono gtk gmail com>]

Hi, all:
    I'm writing a geometry program in Gtkmm. My program create a new thread to carry out a lengthy computation. Meanwhile, I want to show the  step-by-step  computation procedure in a TextView. So I need to update the content of the TextView from the computation thread. From experiences on other GUI toolkits, I figured out that it can not be done directly, and I need something like the Windows PostMessage() function. So what is the gtkmm counterpart of PostMessage()? A gtk C API is also OK.
   Thanks in advance.